Mehrdad Payandeh¹, Edris Sadeghi^{2, 3,}, Masoud Sadeghi^{2, 3}

Background: A 2-deoxy-2-[18F]fluoro-D-glucose (¹⁸FDG) is useful for early metabolic response assessment in various malignancies, including Colorectal Cancer (CRC). Herein, we express that Positron Emission Tomography/Computed (PET-CT) with ¹⁸FDG was very useful for early diagnosis, accuracy and additional value of whole-body in recurrent CRC. Case Report: A 50 years old woman was diagnosed with an adenocarcinoma of the left side colon. She selected for surgery with left sided hemicolectomy. Final pathologic report of adenocarcinoma high risk stage 2 patient, candidate for adjuvant chemotherapy with Folinic acid, Fluorouracil and Oxaliplatin regimen. Her carcino embryonic antigen (CEA) marker at beginning of diagnosis was in normal range but during last year of follow up her CEA marker increased and rising progressive without any complaints by patient. Gastroenterologist tried to diagnosis further secondary staging with lung, brain, abdominal and pelvic contrast computed tomography (CT) scanning but he could not find any lesion in these areas. But After second staging by whole body PET- CT that we suggested it could reveal a multiple lesion uptake in the left lateral sided of the rectum according to a stage IVB disease. For intraperitoneal metastasis adjuvant chemotherapy (CTX) with capecitabine and oxaliplatin was started. At now she is alive without significant abdominal complaint and therefore she treated with maintenance regimen CTX with capecitabine and regorafenib. Conclusion: A ¹⁸F-FDG PET/CT scan was very effective in early diagnosis and High accuracy in finding the precise location of lesion in adenocarcinoma CRC and it can prepare better survival to patients with correctly therapeutic management.

CRC, hemicolectomy, F-FDG PET/CT, intraperitoneal, regorafenib